The present invention generally relates to sealing devices and more particularly relates to a closure device for closing ducts, which are arranged in a housing and in which pressure fluid is conveyed.
German publication DE 44 15 341 A1 discloses a closure device of this type. In the closure device disclosed in this publication, an especially reliable attachment and sealing of a closure member in a housing is achieved because the closure member is fitted in a stepped bore of the housing by means of a combined self-calking and spreading attachment. A closure device of this type necessitates a stepped bore, a closure member of a sophisticated shape, and a special tool for plastically expanding or spreading a collar shaped at the closure member.
U.S. Pat No. 5,853,017 also discloses a generic closure device. The closure device comprises a closing member which has a first recess on its outside periphery for the clinch-type engagement. Besides, another recess for a second clinch-type engagement is provided on the closing member so that a better attachment and sealing is achieved compared to the above-mentioned simple clinch-type engagement. The two recesses are arranged in a spaced relationship so that the flow of material which develops at one recess during the clinching and/or calking operation will not influence the other clinch-type engagement.
Especially in closure caps or cover-type closure members which have a relatively large end surface exposed to the operating pressure, it cannot be excluded that there occurs an automatic release of the closure member from its attachment provided by way of self-calking or clinching, with the consequent risk of not only leakage but also complete malfunction of the closure member and, hence, of the system, for example, a hydraulic brake system for automotive vehicles.
Therefore, an object of the present invention is to avoid the shortcomings of the state of the art and provide a closure device which ensures a particularly safe attachment and sealing of the closure member in the housing along with a simple and inexpensive design.
This object of the present invention is achieved by a closure device of the type mentioned hereinabove because the closure member has at least one further recess at its outside periphery. This second recess favorably accommodates the excess volume of the housing material which is produced when the closure member is clinched.
In case the surface of the housing has been hardened or treated in any other fashion prior to the clinching operation, finery, i.e., flat chips of the housing surface, may peel off in the clinching operation. These chips are also accommodated in the second recess according to the present invention so that the pressure fluid is protected against contaminants which may develop due to clinching.
Another advantage of the present invention can be seen in that no additional increase in the mounting space of the housing is necessary to achieve a bursting strength which is improved compared to the state of the art.
Still another advantage of the present invention involves that the additional recess can be designed on all clinched or calked hydraulic closing devices.
Favorably, the recesses are configured as annular grooves. The axially symmetric arrangement of the closure member in the housing which results from this configuration permits achieving a particularly proper attachment with respect to tilting forces which might cause detachment of the closure member.
In another preferred embodiment of the present invention, the recesses are arranged offset relative to each other in an axial direction. The second recess of the present invention is designed so as to be offset in an axially inward direction in order to accommodate the xe2x80x98bow wavexe2x80x99 which consists of the excess volume of housing material that is produced during the clinching operation and expands inwards. An increase in bursting strength is achieved thereby.
It is preferred that the second recess has a larger volume than the first recess. This permits accommodating a large excess volume of the housing material from the xe2x80x98bow wavexe2x80x99, whereby the off-flow of the excess material is optimized.
For the optimal accommodation of housing material which is moved inwards by the clinching operation, the second recess has a flattened side wall on the external side. This also facilitates the accommodation of the housing material that flows off.
The closure member generally has the shape of a flattened cylinder according to an especially compact embodiment of the present invention.
Besides, in a preferred aspect, the closure member includes a generally cylindrical recess on the side facing the pressure fluid which provides an increased bursting strength in the installed condition and during operation.